SL(4) | Device Drivers Manual | SL(4) |
sl
— Serial Line
IP (SLIP) network interface
pseudo-device sl
The sl
interface allows asynchronous
serial lines to be used as IPv4 network interfaces using the SLIP
protocol.
To use the sl
interface, the administrator
must first create the interface and assign a tty line to it. The
sl
interface is created using the
ifconfig(8)
create
subcommand, and
slattach(8) is used to
assign a tty line to the interface. Once the interface is attached, network
source and destination addresses and other parameters are configured via
ifconfig(8).
The sl
interface can use Van Jacobson TCP
header compression and ICMP filtering. The following flags to
ifconfig(8) control these
properties of a SLIP link:
inet(4), intro(4), ppp(4), ifconfig(8), slattach(8), sliplogin(8), slstats(8)
J. Romkey, A Nonstandard for Transmission of IP Datagrams over Serial Lines: SLIP, RFC, 1055, June 1988.
Van Jacobson, Compressing TCP/IP Headers for Low-Speed Serial Links, RFC, 1144, February 1990.
The sl
device appeared in
NetBSD 1.0.
SLIP can only transmit IPv4 packets between preconfigured hosts on an asynchronous serial link. It has no provision for address negotiation, carriage of additional protocols (e.g. XNS, AppleTalk, DECNET), and is not designed for synchronous serial links. This is why SLIP has been superseded by the Point-to-Point Protocol (PPP), which does all of those things, and much more.
January 18, 2020 | NetBSD 10.99 |